In　order　to　explore　the　thermal　instability　of　Silicon　Carbide　Based　Vertical　Double　Diffused　Metal-Oxide　Field　Effect　Transistor　(SiC　VDMOS)　at　high　temperature,　it　has　been　shown　that　the　temperature　coefficient　of　the　device　saturation　current　has　a　change　from　positive　to　negative,　and　it　is　speculated　that　this　is　related　to　the　change　of　the　threshold　voltage.　Based　on　this,　this　paper　builds　a　high-temperature　test　platform　for　the　electrical　parameters　of　SiC　VDMOS,　and　tests　the　output　and　transfer　characteristics　and　threshold　voltage　of　SiC　VDMOS　in　the　operating　temperature　range　of　300K　~　475K,　which　verifies　the　correctness　of　this　view.　It　is　preliminarily　determined　that　the　change　of　the　threshold　voltage　is　related　to　the　interface　state,　A　1.2　kV　SiC　VDMOS　high　temperature　simulation　model　based　on　Silvaco　TCAD　was　built.　By　using　high-K　dielectrics　with　different　dielectric　constants　including　Al2O3,　Si3N4,　and　HfO2　as　gate　materials,　and　comparing　their　respective　zero　temperature　coefficient　points,　it　is　found　that　the　thermal　stability　of　the　device　is　greatly　improved　after　using　high-K　dielectrics.　The　correctness　of　the　speculation　is　verified.　©　2023　SPIE.